Such an insulation cassette is known from DE 25 21 136 A1. The bolts extends here through the inner and outer limiting plates and all reflection plates of the cassette parts.
According to the introduction to the specification for the state of the art, U.S. Pat. No. 4,659,601 A also pertains to an insulation cassette, in which a bolt passes through all layers of the insulation cassette. It is disadvantageous here that a thermal bridge is formed by the passage of the bolt from the inside of the insulation cassette through all insulation layers up to the outside.
An insulation cassette for the heat insulation of elongated elements with a multilayer insulation made of flat reflection elements is known from EP 0 033 487 A1, wherein each layer of the insulation has at least two flat reflection elements, which overlap at least partly at their ends facing each other.
Insulation cassettes, which are also called reflection metal insulation or all-metal insulation, are used for the heat insulation of pipelines. In particular, such insulation cassettes are used to insulate cooling water pipes of nuclear power plants. A good insulating effect is obtained, especially at high temperatures, because of the multilayer arrangement of the flat reflection elements consisting of reflection foils. Typical areas of application of such insulation cassettes in nuclear power plants are temperature ranges of up to about 350° C.
However, a rather substantial problem arises due to longitudinal thermal expansion because of the comparatively great temperature gradients and the all-metal design of the insulation. Moreover, the insulation cassettes can be prefabricated in an accurately fitting manner up to a certain size only, so that adapters must be made to size on site during assembly for adaptation to the actually needed lengths. For example, insulation cassettes in a stepped fold arrangement are therefore used to compensate the longitudinal thermal expansion in order to make possible a necessary longitudinal expansion. However, the problem with these stepped fold cassettes is that open gaps do occur at times. These gaps are prone to trouble and, in addition, impair the quality of the insulation.